SR20DET misfire

[jing]

My engine started to misfire recently and I was able to trace the misfire to a faulty injector on cylinder #1. I bought a set of used stock 370CC injectors to try out and see if it would fix the problem but it's still misfiring.

Thing is, the guy I bought the injectors off of said they've been sitting around for awhile and wasn't sure if they worked or not..

Well, I tested all 4 of them and none of them seem to work which leads me to ask..

1. How likely is it that the injector plug went bad? How would I go about testing this?

2. Do injectors go bad after sitting around for awhile?

Edit:
ECU's also throwing a code 55 if that means anything...

[0wn3r]

o-rings ok?

I'll be pulling out my fully working 370's from my kouki S14 SR on the 21st...I was going to list them for $85 shipped including paypal fees if you wanna give that a shot. just shoot me a pm

good luck

[johngriff]

12v to one pin, ground the other, you should hear the injector click on and off.

I would be more focused on the spark plug and coil pack wiring, usually that will produce a misfire before a faulty injector.

[jing]

The reason why I thought it'd be the injector is because I pulled off each injector plug while the engine was running to listen for a change in idle. The only one that had no effect when the injector plug was pulled was the 1st cylinder...

Plugs were changed very recently as well. How do I go about checking the coil pack wiring? Only thing I could find in the FSM was to check the ohm resistance of the ignition coils?

[johngriff]

Pull the spark plug on No1 right after it has been running and see if it is wet with fuel. If it is then it is the spark.

[jing]

I won't get a chance to check until tomorrow, but if the plug IS wet with fuel after it's been running, does that mean it needs to be replaced.. yet again?

[0wn3r]

I won't get a chance to check until tomorrow, but if the plug IS wet with fuel after it's been running, does that mean it needs to be replaced.. yet again?

I believe he said look if you're getting spark in that cylinder.

[cotbu]

No....not really! Maybe? After you fix the no sparck issue!
What it does mean,... is it's not the injector. It's a spark problem.

[singlecamslam]

take out the spark plug, plug it into your coil #1, take out fuel pump fuse, have someone crank the motor while you're touching the sparkplug to the engine. You should see a spark, if not than obviously theres no spark and thats your problem.

[johngriff]

take out the spark plug, plug it into your coil #1, take out fuel pump fuse, have someone crank the motor while you're touching the sparkplug to the engine. You should see a spark, if not than obviously theres no spark and thats your problem.

I would unplug the injector leads for that test instead. Even though you pull the fuel pump fuse, there is still pressure in the lines, the remnant pressure will inject fuel, possibly causing a flood, or forcing the engine to turn over when you are not expecting it.

Usually a bad injector will make the car run on 3 cyl all the time, where a spark issue you will get a misfire and break up under acceleration.

Once you have confirmed spark, and especially if you have a tubular manifold, one of the easiest ways to check if a specific cylinder is running lean is to use an infrared temp gun to take a reading off of each cylinders exhaust runner and compare.

One of these with the laser sight.
http://media.digikey.com/photos/TPI%20Photos/TPI%20375.jpg

If you think a coil pack is going bad, you can also compare temps off the top where the white epoxy is.

Ice cold runner compared to others = no fuel / and or spark.
Really HOT runner compared = lean fuel faulty injector.
Cold coil pack, no spark = bad coil pack wiring
Hot coil pack, spark break up = bad coil pack.

The above is a general rule of thumb I have learned, not a bible on SR diagnostics.

[speedfiend]

You guys sure do go through a lot of work to check for spark. First off before I suspected the injectors at all I would definitely make sure that your coilpacks haven't gone bad. This is a major problem with these old motors. Anyways all you have to do is start the motor and while it is idling pull each plug to each coilpack off and listen for a change. This will let you know if you are getting spark on each cylinder.

Just because you pulled the injector plugs and #1 didnt make a change does not necessarily mean that it is the injector. If the coil on #1 has gone out then the injector is just spraying fuel and not being ignited causing your misfire. Therefore by pulling the injector plugs you really havent determined anything but that cylinder one is the one not firing. But you havent determined whether it is a spark issue or a fuel issue.

I just recommend the coilpack test first as it is the easiest thing to check without really pulling anything apart or taking fuses out. Also like I mentioned above it is normally one of the first things to lead to a misfire problem on these motors. Hope this helps and good luck tracking down the problem.
Cameron

[Chrischeezer]

... aaaah

swap the suspected bad injector with another see if the problem follows. if not, you problem is else where

( you can do the same with coilpacks) ;)

[johngriff]

bahhh you will figure it out...

[jing]

Well, it appears to be a spark issue..

I swapped the coilpack with a known good one from a different cylinder but still no good..

[speedfiend]

Well, it appears to be a spark issue..

I swapped the coilpack with a known good one from a different cylinder but still no good..

So you have ruled out the injector being bad? Even if the coil is good and there is no fuel you still wont get fire on that cylinder. Sorry but you never clearly mentioned if you did the injector test to see if the plug was wet with fuel and there isnt spark.
Cameron

[jing]

I pulled the plug from #1 after I ran it for a minute and it was not wet. I thought this was weird so I pulled the plug from a known good cylinder (#2) as well and that wasn't wet either.. ?

I also swapped the injector from the same known good #2 cylinder for the one on #1 but to no avail..

[singlecamslam]

take out the spark plug, plug it into your coil #1, take out fuel pump fuse, have someone crank the motor while you're touching the sparkplug to the engine. You should see a spark, if not than obviously theres no spark and thats your problem.

Did you try that yet? Do it the way Johngriff said. This is the easiest way to check for spark in my opinion cause you can actually see it.

[jing]

Tried that! No spark.

[godsmack]

Ok the easiest way to check for spark is to get another sparkplug, pull the coilpack out, plug new plug in, leave old one in head, stand on side of car, ground plug, have someone start car.

[type-s09]

i am having the same issues with my car. trying to figure it out.

[Nutter_SR20DET]

same here i even ended up pulling the the injector plugs as u had stated with no change except no.1. I was searching 240sxforums.com and im suspecting a faulty power transistor, what do u guys think? i hear its pretty common to replace to complete the swap as well as coils. 1 guy said that his 1st swap had 3 bad coils str8 out the crate so it is possible... let me know if u get a fix or at least better results and ill do the same.

[Nutter_SR20DET]

so i went out and changed the ignitor chip, no change, so i checked coil packs for spark... all getting great spark. but i did notice some air leakage in my intercooler piping so im going to tighten all that down and buy some more Tbolt clamps cuz i snapped one (de de dee) but if yall got anymore ideas let me know

[Nutter_SR20DET]

k well turns out a couple of bolts broke on my headers so i guess i need easy out to get them out then bolt it all up. anyone recommend a specific bolt to hold together cat back exhaust mine keep coming out

[s15specR]

12v to one pin, ground the other, you should hear the injector click on and off.

I would be more focused on the spark plug and coil pack wiring, usually that will produce a misfire before a faulty injector.


Had misfiring issues recently, I changed plugs and redid the grounds for coil pack harness, and it solved the problem

[jing]

'twas my ignitor

[epics13]

had this same issue at first taught it was the sprakplug however it was the injector, i did the unplug each injector test one by one to determine the problem, in my opinion you shouldnt buy used injectors, just get them from the dealer, its like 60 bucks but atleast u now its good.